Biomechanical analysis of gait termination in 11-17year old youth at preferred and fast walking speeds

Strategies for unplanned gait termination at comfortable and fast walking speeds in children with cerebral palsy

Collision avoidance while walking is necessary for safe living, and faster walking speeds tend to increase collision risk. However, gait termination strategies for patients with cerebral palsy (CP), from comfortable to faster speed, remain unexplored. This study aimed to analyze these strategies in children with CP compared to typically developing (TD) children at two different speeds. Study participants included 10 children with CP (mean age, 12.5; five females; mean height, 147.8 cm; mean weight, 41.7 kg) and 10 TD children (mean age, 11.4; nine females; mean height, 142.0 cm; mean weight, 38.1 kg). Effects of walking speed on spatial, force, and temporal parameters were assessed at 100 % (WS1) and 125 % (WS2) speeds of comfortable walking. The TD group exerted a more pronounced braking force at the first step after the stop line appeared on the floor until the contralateral step at both WS1 (P = 0.006) and WS2 (P = 0.019); however, the CP group exerted a more potent force after the second step (WS1: P = 0.026, WS2: P = 0.023) in the anterior-posterior (AP) direction. Additionally, an increase in the center of mass (COM)-center of pressure (COP) divergence in the AP direction (P = 0.032), which decreased in the mediolateral (ML) direction (P = 0.036) at faster walking speeds, influenced the kinetic characteristics of the CP group from WS1 to WS2. The complex adaptations, such as unique braking forces and changes in the COM-COP divergence, suggest that gait interventions should consider the distinctive forces and adopt dynamic balancing strategies to avoid collisions during walking.

Effects of direction cue time and walking speed on spatial-temporal gait adaptations in healthy older and young adults upon approach of turns

BACKGROUND

Hurrying and turning are each associated with falls in older adults. Losing balance sideways when turning increases the likelihood of hip fracture. Yet 99 % of failures when turning unexpectedly have been traced to an inability to curb forward momentum regardless of age.

RESEARCH QUESTION

Do age-based differences exist in spatial-temporal gait adaptations related to medial-lateral (M-L) balance and posterior-anterior (P-A) propulsion upon approach of turns relative to continuing straight, across walking speeds and whether direction is known in advance?

METHODS

Healthy young (n=10) and older adults (n = 10) walked at preferred and fast test speeds while randomly cued for direction either early upon initiating gait or late 1-2 steps before entering a spatially defined turning area. An instrumented 4.6 m carpet recorded spatial-temporal changes up to the penultimate footfall prior to turning 900 or continuing straight.

RESULTS

When approaching the turning zone across interactions of walking test speed, cue time and direction, other than stride-length being shorter in older adults, both age-groups showed similar adjustments in gait speed and stride-length in managing P-A deceleration perturbations, and similar adaptations in right and left heel-to-heel base of support (BOS) in managing M-L balance destabilizing forces. A three-way interaction (p<.027) suggests a similar foot strategy of BOS narrowing may be used approaching turns relative to straight walks when direction is cued early walking fast (p<.020) and late walking preferred speed (p<.014).

SIGNIFICANCE

The findings were interpreted within the context of regulating center of mass acceleration and processing environmental regulatory conditions to maintain a personal space safety margin. The study supports that in otherwise healthy older adults, gait training for turns include practice to not only manage perturbations which accelerate the body sideways but also those which decelerate forward progression.

Gait velocity control using projection mapping for children with spastic diplegia cerebral palsy

BACKGROUND

Gait characteristics in children with cerebral palsy vary according to their individual walking speed. As such, establishing methods to maintain a consistent gait velocity are necessary to evaluate specific intervention effects in this clinical population. Our study aim was to validate the accuracy of projection mapping for guiding gait velocity to a control gait velocity.

METHODS

This was a cross-sectional study of 13 children with cerebral palsy (mean age [standard deviation] of 12.42 [2.31] years). The target velocity was calculated from the average speed obtained across three trials of self-selected walking speed. A virtual reality system with four projectors was used to project an image onto the floor to guide children to match two gait conditions: 100% and 125% velocity of the average speed. Participants completed three gait trials at each velocity under image guidance. Gait velocity was quantified using a 3-dimensional motion capture system. Bland-Altman plots were used to analyze systematic errors and the limits of agreement calculated.

FINDINGS

The results indicated the limits of agreement were acceptable for 0.10 m/s for 100% velocity and 0.12 m/s for 125% velocity. Therefore, projection mapping was effective in guiding children to adjust their gait to the intended velocity.

INTERPRETATION

Projection mapping is a novel method for guiding children with cerebral palsy to walk at a controlled target velocity that may improve the reliability of gait analysis.

Biomechanical Analysis of Unplanned Gait Termination According to a Stop-Signal Task Performance: A Preliminary Study

There is a correlation between cognitive inhibition and compensatory balance response; however, the correlation between response inhibition and gait termination is not clear.

OBJECTIVES

The purpose of this study was to investigate the gait parameters of the lower extremity that occurred during unplanned gait termination (UGT) in two groups classified by the stop-signal reaction time (SSRT).

METHODS

Twenty young adults performed a stop-signal task and an unplanned gait termination separately. UGT required subjects to stop on hearing an auditory cue during randomly selected trials. The spatiotemporal and kinematic gait parameters were compared between the groups during UGT.

RESULTS

In phase one, the fast group had a significantly greater angle and angular velocity of knee flexion and ankle plantar flexion than the slow group (p < 0.05). Phase two showed that the fast group had a significantly greater angle and angular velocity of knee extension than the slow group (p < 0.05). Concerning the correlation analysis, the angle and angular velocity of knee flexion and ankle plantar flexion showed a negative correlation with the SSRT during UGT in phase one (p < 0.05). Phase two showed that the angle and angular velocity of knee extension was negatively correlated with the SSRT during UGT (p < 0.05).

CONCLUSION

The shorter the SSRT, the greater the angle and joint angular velocity of the ankle or knee joint that were prepared and adjusted for gait termination. The correlation between the SSRT and UGT suggests that a participant's capacity to inhibit an incipient finger response is associated with their ability to make a corrective gait pattern in a choice-demanding environment.

Investigating Temporal Kinematic Differences Caused by Unexpected Stimulation during Gait Termination through the Waveform-Level Variance Equality Test

The efficacy of the variance equality test in steady-state gait analysis is well documented; however, temporal information on where differences in variability occur during gait subtasks, especially during gait termination caused by unexpected stimulation, is poorly understood. Therefore, the purpose of the current study was to further verify the efficacy of the waveform-level variance equality test in gait subtasks by comparing temporal kinematical variability between planned gait termination (PGT) and unplanned gait termination (UGT) caused by unexpected stimulation. Thirty-two asymptomatic male subjects were recruited to participate in the study. A Vicon motion capture system was utilized to measure lower extremity kinematics during gait termination tasks with and without unexpected stimulation conditions. The F-statistic for each interval of the temporal kinematic waveform was compared to the critical value using a variance equality test to identify significant differences in the waveform. Comparative tests between two types of gait terminations found that subjects may exhibit greater kinematics variance in most lower limb joints during UGT caused by unexpected stimulation (especially at stimulus delay and reaction phases). Significant greater variances during PGT were exhibited only in the MPJ sagittal and frontal planes at the early stimulus delay phase (4-15% and 1-15%). This recorded dataset of temporal kinematic changes caused by unexpected stimuli during gait termination is essential for interpreting lower limb biomechanical function and injury prediction in relation to UGT. Given the complexity of the gait termination task, which involves both internal and external variability, the variance equality test can be used as a valuable method to compare temporal differences in the variability of biomechanical variables.

A Comparative Biomechanical Analysis during Planned and Unplanned Gait Termination in Individuals with Different Arch Stiffnesses

Although values of arch stiffness index (ASI) have been used to evaluate arch structure and injury susceptibility, investigations are limited regarding the influence of ASI on biomechanical characteristics during gait termination, which involves a challenging balance transition from walking to standing. This study aimed to explore plantar pressure distribution and lower extremity joint kinematic differences between individuals with both a stiff and flexible arch (SA and FA, respectively) during planned and unplanned gait termination (PGT and UGT, respectively). Following the calculation of ASI, sixty-five asymptomatic male subjects were classified and participated in two types of gait termination tests to acquire kinematic and plantar pressure data. Parameters were compared between SA and FA using a two-way ANOVA during PGT and UGT, respectively. UGT was found to have a larger range of motion on the hip joint in the sagittal plane and the knee joint in the transverse plane when compared with PGT. The differences in the kinematic characteristics of the lower limb joints caused by the difference in arch stiffness are mainly concentrated in the ankle and metatarsophalangeal joints. Plantar pressure data, represented by the maximum pressure, showed significant differences in the forefoot and rearfoot areas. These results suggest that ASI could change freedom of motion of the lower limb joints, and UGT tends to conduct a compensatory adjustment for the lower extremity kinetic chain. An understanding of the biomechanical characteristics of arch structures may provide additional insights into foot function and injury prediction during gait termination.

Muscle Co-Activation around the Knee during Different Walking Speeds in Healthy Females

The purpose of this study was to examine the changes in co-activation around the knee joint during different walking speeds in healthy females using the co-activation index. Ten healthy females (age: 21.20 ± 7.21 years, height: 164.00 ± 4.00 cm, mass: 60.60 ± 4.99 kg) participated in this study and performed three walking speeds (slow, normal, and fast). A Qualisys 11-camera motion analysis system sampling at a frequency of 200 Hz was synchronized with a Trigno EMG Wireless system operating at a 2000 Hz sampling frequency. A significant decrease in the co-activation index of thigh muscles was observed between the slow and fast, and between the normal and fast, walking speeds during all walking phases. A non-significant difference was observed between the slow and normal walking speeds during most walking phases, except the second double support phase, during which the difference was significant. A negative relationship was found between walking speed and the co-activation index of thigh muscles in all speeds during walking phases: first double support (r = −0.3386, p < 0.001), single support (r = −0.2144, p < 0.01), second double support (r = −0.4949, p < 0.001), and Swing (r = −0.1639, p < 0.05). In conclusion, the results indicated high variability of thigh muscle co-activation in healthy females during the different walking speeds, and a decrease in the co-activation of the thigh muscles with the increase of speed.

Effects of walking speed on gait biomechanics in healthy participants: a systematic review and meta-analysis

BACKGROUND

Understanding the effects of gait speed on biomechanical variables is fundamental for a proper evaluation of alterations in gait, since pathological individuals tend to walk slower than healthy controls. Therefore, the aim of the study was to perform a systematic review of the effects of gait speed on spatiotemporal parameters, joint kinematics, joint kinetics, and ground reaction forces in healthy children, young adults, and older adults.

METHODS

A systematic electronic search was performed on PubMed, Embase, and Web of Science databases to identify studies published between 1980 and 2019. A modified Quality Index was applied to assess methodological quality, and effect sizes with 95% confidence intervals were calculated as the standardized mean differences. For the meta-analyses, a fixed or random effect model and the statistical heterogeneity were calculated using the I2 index.

RESULTS

Twenty original full-length studies were included in the final analyses with a total of 587 healthy individuals evaluated, of which four studies analyzed the gait pattern of 227 children, 16 studies of 310 young adults, and three studies of 59 older adults. In general, gait speed affected the amplitude of spatiotemporal gait parameters, joint kinematics, joint kinetics, and ground reaction forces with a decrease at slow speeds and increase at fast speeds in relation to the comfortable speed. Specifically, moderate-to-large effect sizes were found for each age group and speed: children (slow, - 3.61 to 0.59; fast, - 1.05 to 2.97), young adults (slow, - 3.56 to 4.06; fast, - 4.28 to 4.38), and older adults (slow, - 1.76 to 0.52; fast, - 0.29 to 1.43).

CONCLUSIONS

This review identified that speed affected the gait patterns of different populations with respect to the amplitude of spatiotemporal parameters, joint kinematics, joint kinetics, and ground reaction forces. Specifically, most of the values analyzed decreased at slower speeds and increased at faster speeds. Therefore, the effects of speed on gait patterns should also be considered when comparing the gait analysis of pathological individuals with normal or control ones.

A simple bipedal model for studying control of gait termination

We study the control of human gait termination with a simple bipedal locomotion model. Several control strategies have been proposed for gait termination. However, the relative importance of these strategies has not been evaluated in models of human gait. Here we extend the bipedal spring mass walking model in a least parameter fashion and study three explicit control strategies for gait termination, including the shortening of the final step, braking at the ankle, and extending the knee. Applying the strategies separately, we find that only braking at the ankle reduces the propulsive force enough to transition into quiet standing. In combination with the other two strategies, we observe that the range of control parameters suitable for gait termination increases, especially when the ankle control is applied intermittently by taking advantage of passive stabilizing dynamics. We further show the resulting model behavior is compatible with several experimental observations about the human center of mass dynamics and leg forces during gait termination, and discuss model improvements to correct mismatches. The proposed model may serve as a starting point for more advanced models that can provide a deeper understanding of human control strategies during gait termination.